Re: [PATCH/RFC v2 i2c/for-next] i2c: rcar: Add per-Generation fallback bindings

[Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>]

On Thu, Dec 01, 2016 at 04:55:13PM +0100, Geert Uytterhoeven wrote:
> Hi Simon,
> 
> On Thu, Dec 1, 2016 at 4:41 PM, Simon Horman <horms+renesas-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org> wrote:
> > In the case of Renesas R-Car hardware we know that there are generations of
> > SoCs, e.g. Gen 2 and Gen 3. But beyond that its not clear what the
> > relationship between IP blocks might be. For example, I believe that
> > r8a7790 is older than r8a7791 but that doesn't imply that the latter is a
> > descendant of the former or vice versa.
> >
> > We can, however, by examining the documentation and behaviour of the
> > hardware at run-time observe that the current driver implementation appears
> > to be compatible with the IP blocks on SoCs within a given generation.
> >
> > For the above reasons and convenience when enabling new SoCs a
> > per-generation fallback compatibility string scheme being adopted for
> > drivers for Renesas SoCs.
> >
> > Also deprecate renesas,i2c-rcar. It seems poorly named as it is only
> > compatible with R-Car Gen 1. It also appears unused in mainline.
> >
> > Signed-off-by: Simon Horman <horms+renesas-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>
> > ---
> > Include accidently omitted i2c-rcar.c portion of patch
> > ---
> >  Documentation/devicetree/bindings/i2c/i2c-rcar.txt | 32 ++++++++++++++--------
> >  drivers/i2c/busses/i2c-rcar.c                      |  5 +++-
> >  2 files changed, 24 insertions(+), 13 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
> > index 239632a0d709..8c679b17c4c6 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
> > @@ -1,17 +1,25 @@
> >  I2C for R-Car platforms
> >
> >  Required properties:
> > -- compatible: Must be one of
> > -       "renesas,i2c-rcar"
> > -       "renesas,i2c-r8a7778"
> > -       "renesas,i2c-r8a7779"
> > -       "renesas,i2c-r8a7790"
> > -       "renesas,i2c-r8a7791"
> > -       "renesas,i2c-r8a7792"
> > -       "renesas,i2c-r8a7793"
> > -       "renesas,i2c-r8a7794"
> > -       "renesas,i2c-r8a7795"
> > -       "renesas,i2c-r8a7796"
> > +- compatible:
> > +       "renesas,i2c-r8a7778" if the device is a part of a R8A7778 SoC.
> > +       "renesas,i2c-r8a7779" if the device is a part of a R8A7797 SoC.
> > +       "renesas,i2c-r8a7790" if the device is a part of a R8A7790 SoC.
> > +       "renesas,i2c-r8a7791" if the device is a part of a R8A7791 SoC.
> > +       "renesas,i2c-r8a7792" if the device is a part of a R8A7792 SoC.
> > +       "renesas,i2c-r8a7793" if the device is a part of a R8A7793 SoC.
> > +       "renesas,i2c-r8a7794" if the device is a part of a R8A7794 SoC.
> > +       "renesas,i2c-r8a7795" if the device is a part of a R8A7795 SoC.
> > +       "renesas,i2c-r8a7796" if the device is a part of a R8A7796 SoC.
> > +       "renesas,i2c-rcar-gen1" for a generic R-Car Gen1 compatible device.
> > +       "renesas,i2c-rcar-gen2" for a generic R-Car Gen2 compatible device.
> > +       "renesas,i2c-rcar-gen3" for a generic R-Car Gen3 compatible device.
> 
> "renesas,rcar-gen1-i2c" etc.
> 
> > +       "renesas,i2c-rcar" (deprecated)
> > +
> > +       When compatible with the generic version, nodes must list the
> > +       SoC-specific version corresponding to the platform first followed
> > +       by the generic version.
> > +
> >  - reg: physical base address of the controller and length of memory mapped
> >    region.
> >  - interrupts: interrupt specifier.
> > @@ -33,7 +41,7 @@ Examples :
> >  i2c0: i2c@e6508000 {
> >         #address-cells = <1>;
> >         #size-cells = <0>;
> > -       compatible = "renesas,i2c-r8a7791";
> > +       compatible = "renesas,i2c-r8a7791", "renesas,i2c-rcar-gen2";
> 
> "renesas,rcar-gen2-i2c"
> 
> >         reg = <0 0xe6508000 0 0x40>;
> >         interrupts = <0 287 IRQ_TYPE_LEVEL_HIGH>;
> >         clocks = <&mstp9_clks R8A7791_CLK_I2C0>;
> > diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
> > index 726615e54f2a..622def6b43e2 100644
> > --- a/drivers/i2c/busses/i2c-rcar.c
> > +++ b/drivers/i2c/busses/i2c-rcar.c
> > @@ -793,7 +793,6 @@ static const struct i2c_algorithm rcar_i2c_algo = {
> >  };
> >
> >  static const struct of_device_id rcar_i2c_dt_ids[] = {
> > -       { .compatible = "renesas,i2c-rcar", .data = (void *)I2C_RCAR_GEN1 },
> >         { .compatible = "renesas,i2c-r8a7778", .data = (void *)I2C_RCAR_GEN1 },
> >         { .compatible = "renesas,i2c-r8a7779", .data = (void *)I2C_RCAR_GEN1 },
> >         { .compatible = "renesas,i2c-r8a7790", .data = (void *)I2C_RCAR_GEN2 },
> > @@ -803,6 +802,10 @@ static const struct of_device_id rcar_i2c_dt_ids[] = {
> >         { .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
> >         { .compatible = "renesas,i2c-r8a7795", .data = (void *)I2C_RCAR_GEN3 },
> >         { .compatible = "renesas,i2c-r8a7796", .data = (void *)I2C_RCAR_GEN3 },
> > +       { .compatible = "renesas,i2c-rcar", .data = (void *)I2C_RCAR_GEN1 },    // Deprecated
> > +       { .compatible = "renesas,rcar-gen1-i2c", .data = (void *)I2C_RCAR_GEN1 },
> > +       { .compatible = "renesas,rcar-gen2-i2c", .data = (void *)I2C_RCAR_GEN2 },
> > +       { .compatible = "renesas,rcar-gen3-i2c", .data = (void *)I2C_RCAR_GEN3 },
> 
> The driver does it right ;-)

Sorry, I switched things around at some point but it looks
like I only did half the job.
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